The present invention relates to a system for correcting the effect of altitude on an internal combustion engine with a supercharging device for a vehicle.
An internal combustion engine for an automobile is provided with a supercharger driven by an exhaust-gas turbine having a small capacity, so that the supercharger may start to operate at a low engine speed. As a result of such a supercharger, supercharging pressure increases excessively with an increase in the engine speed as shown by the dotted line in FIG. 1, which may cause a breakdown of the engine. In order to avoid such damage, for example, a system has been proposed by Japanese Utility Model Application Publication No. 47-38660. The system comprises a bypass provided in the exhaust gas turbine for the supercharger, a waste gate valve in the bypass, and an actuator for operating the waste gate valve. The actuator comprises a diaphragm operatively connected to the waste gate valve, an atmospheric chamber and a supercharging pressure chamber partitioned by the diaphragm. The diaphragm is deflected by the difference between the atmospheric pressure and the supercharging pressure when the supercharging pressure increases. Thus, the actuator operates to open the waste gate valve when the engine speed is higher than a predetermined speed. Accordingly, an increase of the supercharging pressure is prevented as shown by "a" in FIG. 1.
However, since the atmospheric pressure is low at high altitude, the actuator operates at a low supercharging pressure as shown by "b" in FIG. 1. Therefore, the low supercharging pressure does not effectively provide an increase in the engine output.